Osmocom Packet control Unit (PCU): Network-side GPRS (RLC/MAC); BTS- or BSC-colocated https://osmocom.org/projects/osmopcu
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osmo-pcu/src/tbf_ul_ack_fsm.c

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/* tbf_ul_ack_fsm.c
*
* Copyright (C) 2021 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
* Author: Pau Espin Pedrol <pespin@sysmocom.de>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <unistd.h>
#include <talloc.h>
#include <osmocom/core/bitvec.h>
#include <tbf_ul_ack_fsm.h>
#include <gprs_rlcmac.h>
#include <gprs_debug.h>
#include <gprs_ms.h>
#include <encoding.h>
#include <bts.h>
#include <tbf.h>
#include <tbf_ul.h>
#include <tbf_ul_ack_fsm.h>
#define X(s) (1 << (s))
const struct osmo_tdef_state_timeout tbf_ul_ack_fsm_timeouts[32] = {
[TBF_UL_ACK_ST_NONE] = {},
[TBF_UL_ACK_ST_SCHED_UL_ACK] = {},
[TBF_UL_ACK_ST_WAIT_ACK] = {},
};
const struct value_string tbf_ul_ack_fsm_event_names[] = {
{ TBF_UL_ACK_EV_SCHED_ACK, "SCHED_ACK" },
{ TBF_UL_ACK_EV_CREATE_RLCMAC_MSG, "CREATE_RLCMAC_MSG" },
{ TBF_UL_ACK_EV_RX_CTRL_ACK, "RX_CTRL_ACK" },
{ TBF_UL_ACK_EV_POLL_TIMEOUT, "POLL_TIMEOUT" },
{ 0, NULL }
};
static struct msgb *create_ul_ack_nack(const struct tbf_ul_ack_fsm_ctx *ctx,
const struct tbf_ul_ack_ev_create_rlcmac_msg_ctx *d,
bool final)
{
struct msgb *msg;
int rc;
unsigned int rrbp = 0;
uint32_t new_poll_fn = 0;
struct gprs_rlcmac_tbf *tbf = (struct gprs_rlcmac_tbf *)ctx->tbf;
struct GprsMs *ms = tbf_ms(tbf);
if (final) {
rc = tbf_check_polling(tbf, d->fn, d->ts, &new_poll_fn, &rrbp);
if (rc < 0)
return NULL;
}
msg = msgb_alloc(23, "rlcmac_ul_ack");
if (!msg)
return NULL;
struct bitvec *ack_vec = bitvec_alloc(23, tbf);
if (!ack_vec) {
msgb_free(msg);
return NULL;
}
bitvec_unhex(ack_vec, DUMMY_VEC);
write_packet_uplink_ack(ack_vec, ctx->tbf, final, rrbp);
bitvec_pack(ack_vec, msgb_put(msg, 23));
bitvec_free(ack_vec);
/* TS 44.060 7a.2.1.1: "The contention resolution is completed on
* the network side when the network receives an RLC data block that
* comprises the TLLI value that identifies the mobile station and the
* TFI value associated with the TBF."
* However, it's handier for us to mark contention resolution success
* here since according to spec upon rx UL ACK is the time at which MS
* realizes contention resolution succeeds. */
if (ms_tlli(ms) != GSM_RESERVED_TMSI)
ul_tbf_contention_resolution_success(ctx->tbf);
if (final) {
tbf_set_polling(tbf, new_poll_fn, d->ts, PDCH_ULC_POLL_UL_ACK);
LOGPTBFUL(tbf, LOGL_DEBUG,
"Scheduled UL Acknowledgement polling on PACCH (FN=%d, TS=%d)\n",
new_poll_fn, d->ts);
}
return msg;
}
static void st_none(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
switch (event) {
case TBF_UL_ACK_EV_SCHED_ACK:
tbf_ul_ack_fsm_state_chg(fi, TBF_UL_ACK_ST_SCHED_UL_ACK);
break;
default:
OSMO_ASSERT(0);
}
}
static void st_sched_ul_ack(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
struct tbf_ul_ack_fsm_ctx *ctx = (struct tbf_ul_ack_fsm_ctx *)fi->priv;
struct gprs_rlcmac_tbf *tbf = (struct gprs_rlcmac_tbf *)ctx->tbf;
struct tbf_ul_ack_ev_create_rlcmac_msg_ctx *data_ctx;
bool final;
switch (event) {
case TBF_UL_ACK_EV_SCHED_ACK:
LOGPTBFUL(tbf, LOGL_DEBUG,
"Sending Ack/Nack already scheduled, no need to re-schedule\n");
break;
case TBF_UL_ACK_EV_CREATE_RLCMAC_MSG:
data_ctx = (struct tbf_ul_ack_ev_create_rlcmac_msg_ctx *)data;
final = tbf_state(tbf) == TBF_ST_FINISHED;
data_ctx->msg = create_ul_ack_nack(ctx, data_ctx, final);
if (!data_ctx->msg)
return;
if (final) /* poll set */
tbf_ul_ack_fsm_state_chg(fi, TBF_UL_ACK_ST_WAIT_ACK);
else
tbf_ul_ack_fsm_state_chg(fi, TBF_UL_ACK_ST_NONE);
break;
default:
OSMO_ASSERT(0);
}
}
static void st_wait_ctrl_ack(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
struct tbf_ul_ack_fsm_ctx *ctx = (struct tbf_ul_ack_fsm_ctx *)fi->priv;
struct gprs_rlcmac_tbf *tbf = (struct gprs_rlcmac_tbf *)ctx->tbf;
switch (event) {
case TBF_UL_ACK_EV_SCHED_ACK:
/* ignore, we are in the middle of waiting for a response */
break;
case TBF_UL_ACK_EV_RX_CTRL_ACK:
tbf_ul_ack_fsm_state_chg(fi, TBF_UL_ACK_ST_NONE);
break;
case TBF_UL_ACK_EV_POLL_TIMEOUT:
LOGPTBF(tbf, LOGL_NOTICE,
"Timeout for polling PACKET CONTROL ACK for PACKET UPLINK ACK: %s\n",
tbf_rlcmac_diag(tbf));
/* Reschedule Ul Ack/NAck */
tbf_ul_ack_fsm_state_chg(fi, TBF_UL_ACK_ST_SCHED_UL_ACK);
break;
default:
OSMO_ASSERT(0);
}
}
static int tbf_ul_ack_fsm_timer_cb(struct osmo_fsm_inst *fi)
{
switch (fi->T) {
default:
OSMO_ASSERT(0);
}
return 0;
}
static struct osmo_fsm_state tbf_ul_ack_fsm_states[] = {
[TBF_UL_ACK_ST_NONE] = {
.in_event_mask =
X(TBF_UL_ACK_EV_SCHED_ACK),
.out_state_mask =
X(TBF_UL_ACK_ST_SCHED_UL_ACK),
.name = "NONE",
.action = st_none,
},
[TBF_UL_ACK_ST_SCHED_UL_ACK] = {
.in_event_mask =
X(TBF_UL_ACK_EV_SCHED_ACK) |
X(TBF_UL_ACK_EV_CREATE_RLCMAC_MSG),
.out_state_mask =
X(TBF_UL_ACK_ST_NONE) |
X(TBF_UL_ACK_ST_WAIT_ACK),
.name = "SCHED_UL_ACK",
.action = st_sched_ul_ack,
},
[TBF_UL_ACK_ST_WAIT_ACK] = {
.in_event_mask =
X(TBF_UL_ACK_EV_SCHED_ACK) |
X(TBF_UL_ACK_EV_RX_CTRL_ACK) |
X(TBF_UL_ACK_EV_POLL_TIMEOUT),
.out_state_mask =
X(TBF_UL_ACK_ST_NONE) |
X(TBF_UL_ACK_ST_SCHED_UL_ACK),
.name = "WAIT_ACK",
.action = st_wait_ctrl_ack,
},
};
struct osmo_fsm tbf_ul_ack_fsm = {
.name = "UL_ACK_TBF",
.states = tbf_ul_ack_fsm_states,
.num_states = ARRAY_SIZE(tbf_ul_ack_fsm_states),
.timer_cb = tbf_ul_ack_fsm_timer_cb,
.log_subsys = DTBFUL,
.event_names = tbf_ul_ack_fsm_event_names,
};
static __attribute__((constructor)) void tbf_ul_ack_fsm_init(void)
{
OSMO_ASSERT(osmo_fsm_register(&tbf_ul_ack_fsm) == 0);
}
struct msgb *tbf_ul_ack_create_rlcmac_msg(const struct gprs_rlcmac_tbf *tbf, uint32_t fn, uint8_t ts)
{
int rc;
struct tbf_ul_ack_ev_create_rlcmac_msg_ctx data_ctx = {
.fn = fn,
.ts = ts,
.msg = NULL,
};
OSMO_ASSERT(tbf_direction(tbf) == GPRS_RLCMAC_UL_TBF);
rc = osmo_fsm_inst_dispatch(tbf_ul_ack_fi((const struct gprs_rlcmac_ul_tbf *)tbf), TBF_UL_ACK_EV_CREATE_RLCMAC_MSG, &data_ctx);
if (rc != 0 || !data_ctx.msg)
return NULL;
return data_ctx.msg;
}
bool tbf_ul_ack_rts(const struct gprs_rlcmac_tbf *tbf)
{
struct osmo_fsm_inst *fi = tbf_ul_ack_fi((const struct gprs_rlcmac_ul_tbf *)tbf);
return fi->state == TBF_UL_ACK_ST_SCHED_UL_ACK;
}
/* Did we already send the Final ACK and we are waiting for its confirmation (CTRL ACK) ? */
bool tbf_ul_ack_waiting_cnf_final_ack(const struct gprs_rlcmac_tbf* tbf)
{
OSMO_ASSERT(tbf_direction(tbf) == GPRS_RLCMAC_UL_TBF);
struct osmo_fsm_inst *fi = tbf_ul_ack_fi((const struct gprs_rlcmac_ul_tbf *)tbf);
return fi->state == TBF_UL_ACK_ST_WAIT_ACK;
}
bool tbf_ul_ack_exp_ctrl_ack(const struct gprs_rlcmac_tbf *tbf, uint32_t fn, uint8_t ts)
{
struct osmo_fsm_inst *fi = tbf_ul_ack_fi((const struct gprs_rlcmac_ul_tbf *)tbf);
return fi->state == TBF_UL_ACK_ST_WAIT_ACK;
/* FIXME: validate FN and TS match: && ctx->poll_fn = fn && ctx->poll_ts == ts */
}